Seat-track assembly

ABSTRACT

A seat-track assembly is provided and may include a first track member having a series of locking features and a second track member slidably supported by the first track member. The seat-track assembly may also include a locking mechanism having locking pawls movable between a locked state engaged with the locking features to restrict relative movement between the first and second track members and an unlocked state disengaged from the locking features to permit relative movement between the first and second track members. The locking pawls may each include locking elements that are received within respective ones of the series of locking features in the locked state such that the locking elements restrict relative movement between the first track member and the second track member in two directions when the locking pawls are in the locked state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.16/390,264, filed Apr. 22, 2019, which is a continuation of U.S.application Ser. No. 14/886,392, filed on Oct. 19, 2015, which is acontinuation-in-part of U.S. application Ser. No. 14/349,817, filed onApr. 4, 2014, which is a National Stage of International Application No.PCT/US2012/060605, filed on Oct. 17, 2012, which claims the benefit ofU.S. Provisional Application No. 61/548,042, filed on Oct. 17, 2011. Theentire disclosures of the above applications are incorporated herein byreference.

FIELD

The present disclosure relates to seat-track assemblies and moreparticularly to a locking mechanism for a seat-track assembly.

BACKGROUND

This section provides background information related to the presentdisclosure and is not necessarily prior art.

Modern vehicles typically include at least one seat assembly that ismovable in a fore-aft direction relative to a floorpan of a vehicle. Forexample, a sport utility vehicle or minivan may incorporate adriver-seat assembly, a passenger-seat assembly, and a second-row seatassembly that are all movable in a fore-aft direction relative to thefloorpan of the vehicle. Movement of the foregoing seat assembliespermits a user to adjust a position of the respective seat assemblyrelative to vehicle controls and/or to permit access to an areagenerally behind the seat assembly. For example, adjustment of adriver-seat assembly relative to a floorpan of a vehicle permits thedriver to move the seat assembly closer to or farther away from asteering wheel of the vehicle. Likewise, permitting adjustment of apassenger-seat assembly in a fore-aft direction relative to a floorpanof a vehicle permits a user to adjust a position of the passenger seatrelative to controls of the vehicle and/or to access an area behind thepassenger seat to gain access to a second-row seat assembly or to gainaccess to a storage compartment of the vehicle.

Seat assemblies that are permitted to move in a fore-aft directionrelative to a floorpan of a vehicle typically include a seat-trackassembly that provides for such movement. Such seat-track assembliestypically include a first component that is fixed to a floorpan of avehicle and a second component that is fixed for movement with a vehicleseat. The second component is selectively movable relative to the firstcomponent and, thus, permits selective movement of the seat assemblyrelative to the first component. Permitting movement of the secondcomponent and seat assembly relative to the first component likewisepermits movement of the seat assembly and second component relative tothe floorpan of the vehicle.

While conventional seat assemblies incorporate a seat-track assemblythat permits for selective adjustment of a vehicle seat in a fore-aftdirection relative to a floorpan of a vehicle, such seat-trackassemblies do not provide an occupant with the ability to adjust aposition of the seat assembly relative to the floorpan in smallincrements. Further, conventional seat assemblies typically require auser to move the seat assembly greater than five millimeters (5 mm) ineither the fore or aft direction following release of an actuationmechanism to allow a locking mechanism associated with the seat-trackassembly to properly engage and fix a position of the seat assemblyrelative to the floorpan. Finally, while conventional seat-trackassemblies adequately fix a position of a seat assembly relative to afloorpan of a vehicle, such seat-track assemblies may experience adegree of rattling or “chucking” during use caused by relative movementbetween the various components of the seat-track assembly, therebycreating undesirable noise during use.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

In one form, the present disclosure provides a seat-track assembly thatmay include a first track member having a series of locking features anda second track member slidably supported by the first track member. Alocking mechanism may be disposed at least partially between the firsttrack member and the second track member and may include at least twolocking pawls movable between a locked state engaged with the lockingfeatures to restrict relative movement between the first track memberand the second track member and an unlocked state disengaged from thelocking features to permit relative movement between the first trackmember and the second track member. The at least two locking pawls mayeach include at least two locking elements that are received withinrespective ones of the series of locking features in the locked statesuch that each of the locking elements simultaneously restrict relativemovement between the first track member and the second track member intwo directions when the locking pawls are in the locked state.

In another form, the present disclosure provides a seat-track assemblythat may seat-track assembly is provided and may include a first trackmember having a series of locking features and a second track memberslidably supported by the first track member. A locking mechanism may bedisposed at least partially between the first track member and thesecond track member and may include at least two locking pawls movablebetween a locked state engaged with the locking features to restrictrelative movement between the first track member and the second trackmember and an unlocked state disengaged from the locking features topermit relative movement between the first track member and the secondtrack member. The at least two locking pawls may each include at leasttwo locking elements that are in contact with the first track member attwo locations within each of the locking features when in the lockedstate.

In another form, the present disclosure provides a seat-track assemblythat may include first and second track members and a locking mechanism.The first track member may include a series of locking features. Thesecond track member may be slidably supported by the first track member.The locking mechanism may be disposed at least partially between thefirst track member and the second track member and may include first,second and third locking pawls that are movable independently of eachother between a locked state engaged with the locking features torestrict relative movement between the first track member and the secondtrack member and an unlocked state disengaged from the locking featuresto permit relative movement between the first track member and thesecond track member. Each of the first, second and third locking pawlsmay include a locking element that is received within a respective oneof the series of locking features in the locked state. The lockingfeatures may each have a width that is at least double a width of eachof the locking elements such that the locking elements of two of thefirst, second and third locking pawls simultaneously restrict relativemovement between the first track member and the second track member intwo directions when the two of the locking pawls are in the lockedstate. At least one of the locking pawls may be in the unlocked state atany given time.

In some configurations, a plurality of locking elements extend fromopposite ends of each of the locking pawls and are received withinrespective locking features when the locking pawls are in the lockedstate.

In some configurations, only a single locking element extends from eachend of each of the locking pawls.

In some configurations, the seat-track includes an actuator operable toselectively apply a force on any two of the first, second and thirdlocking pawls to maintain the two of the locking pawls in the unlockedstate.

In some configurations, at least one of the locking pawls is in thelocked state following release of the force regardless of thepositioning of the second track member relative to the first trackmember.

In some configurations, relative movement between the first track memberand the second track member is limited to half of the width of one ofthe locking features following release of the force before the lockingelements of two of the locking pawls are received within respective onesof the locking features.

In some configurations, the actuator includes an elongated bar extendingparallel to longitudinal axes of the first and second track members, andthe elongated bar includes a peg extending perpendicular to thelongitudinal axes and through an aperture in the second track member.

In some configurations, the elongated bar selectively applies a force onthe locking pawls to maintain the locking pawls in the unlocked state.

In some configurations, the seat-track assembly includes a housingattached to the second track member and disposed between the first andsecond track members. The housing may define a cavity in which theelongated bar is movably disposed. Each of the locking pawls may includean actuation arm that extends into the cavity and reciprocates thereinas the locking pawls move between the locked and unlocked states.

In another form, the present disclosure provides a seat-track assemblythat may include first and second track members and a locking mechanism.The first track member may include a series of locking features. Thesecond track member may be slidably supported by the first track member.The locking mechanism may be disposed at least partially between thefirst track member and the second track member and including first andsecond locking pawls that are movable independently of each otherbetween a locked state engaged with the locking features to restrictrelative movement between the first track member and the second trackmember and an unlocked state disengaged from the locking features topermit relative movement between the first track member and the secondtrack member. Each of the locking pawls may include locking elementsthat are received within a respective one of the series of lockingfeatures in the locked state. The first locking pawl may include aplurality of locking elements extending from opposite ends of the firstlocking pawl. The second locking pawl may include only a single lockingelement extending from each end of the second locking pawl.

In some configurations, the locking features each have a width that isgreater than a width of one of the locking elements of the first lockingpawl and substantially equal to a width of one of the locking elementsof the second locking pawl.

In some configurations, the seat-track assembly includes a third lockingpawl movable independently of the first and second locking pawls betweenthe locked and unlocked states.

In some configurations, the second locking pawl is disposed between thefirst and third locking pawls.

In some configurations, the seat-track assembly includes an actuatoroperable to selectively apply a force on any two of the first, secondand third locking pawls to maintain the two of the locking pawls in theunlocked state.

In some configurations, at least one of the locking pawls is in thelocked state following release of the force regardless of thepositioning of the second track member relative to the first trackmember.

In some configurations, relative movement between the first track memberand the second track member is limited to half of the width of one ofthe locking features following release of the force before the lockingelements of two of the locking pawls are received within respective onesof the locking features.

In some configurations, the seat-track assembly includes an actuatoroperable to selectively apply a force on the locking pawls to maintainthe locking pawls in the unlocked state.

In some configurations, the actuator includes an elongated bar extendingparallel to longitudinal axes of the first and second track members. Theelongated bar may include a peg extending perpendicular to thelongitudinal axes and through an aperture in the second track member.

In some configurations, the seat-track assembly includes a housingattached to the second track member and disposed between the first andsecond track members. The housing may define a cavity in which theelongated bar is movably disposed.

In some configurations, each of the locking pawls includes an actuationarm that extends into the cavity and reciprocates therein as the lockingpawls move between the locked and unlocked states.

In some configurations, the first track member and the second trackmember are movable in two, opposite directions relative to one anotheralong an axis when the locking mechanism is in the unlocked state.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a partial perspective view of a seat assembly incorporating aseat-track assembly in accordance with the principles of the presentdisclosure;

FIG. 2 is a perspective view of a track assembly of the seat-trackassembly of FIG. 1;

FIG. 3 is a partial perspective view of the track assembly of FIG. 2;

FIG. 4 is a cross-sectional view of the track assembly of FIG. 3 takenalong line 4-4;

FIG. 5 is an exploded view of the track assembly of FIG. 3;

FIG. 6 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 7 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 8 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 9 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 10 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 11 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 12 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 13 is a perspective view of a locking pawl of the track assembly ofFIG. 2;

FIG. 14 is a partial perspective view of the track assembly of FIG. 2showing two locking pawls in a raised and locked state;

FIG. 15 is a cross-sectional view of the track assembly of FIG. 14 takenalong line 15-15;

FIG. 16 is a cross-sectional view of the track assembly of FIG. 14 takenalong line 16-16;

FIG. 17 is a schematic representation of a portion of a track of thetrack assembly of FIG. 2 illustrating locking features;

FIG. 18 is a partial perspective view of a seat assembly incorporating aseat-track assembly in accordance with the principles of the presentdisclosure;

FIG. 19 is a perspective view of a track assembly of the seat-trackassembly of FIG. 18;

FIG. 20 is a cross-sectional view of the track assembly of FIG. 18 takenalong line 20-20;

FIG. 21 is an exploded view of the track assembly of FIG. 19;

FIG. 22 is a partial cross-sectional view of the track assembly of FIG.18 in an unlocked state taken along line 22-22;

FIG. 23 is a partial cross-sectional view of the track assembly of FIG.18 in a locked state taken along line 23-23;

FIG. 24 is a partial cross-sectional view of the track assembly of FIG.18 in a locked state taken along line 24-24;

FIG. 25 is a schematic representation of a portion of a track of thetrack assembly of FIG. 18 illustrating locking features;

FIG. 26 is an exploded perspective view of a locking mechanism inaccordance with the principles of the present disclosure;

FIG. 27 is a partial cross-sectional view of the locking mechanism ofFIG. 26 installed in a seat-track assembly;

FIG. 28 is a cross-sectional view of a portion of a track of theseat-track assembly of FIG. 27 illustrating locking features;

FIG. 29 is an exploded perspective view of a locking mechanism inaccordance with the principles of the present disclosure;

FIG. 30 is a partial cross-sectional view of the locking mechanism ofFIG. 29 installed in a seat-track assembly;

FIG. 31 is a cross-sectional view of a portion of a track of theseat-track assembly of FIG. 30 in a first position;

FIG. 32 is a cross-sectional view of a portion of the track in a secondposition;

FIG. 33 is a cross-sectional view of a portion of the track in a thirdposition;

FIG. 34 is an exploded perspective view of a locking mechanism inaccordance with the principles of the present disclosure;

FIG. 35 is a partial cross-sectional view of the locking mechanism ofFIG. 34 installed in a seat-track assembly;

FIG. 36 is a cross-sectional view of a portion of a track of theseat-track assembly of FIG. 35 in a first position;

FIG. 37 is a cross-sectional view of a portion of the track in a secondposition;

FIG. 38 is a cross-sectional view of a portion of the track in a thirdposition;

FIG. 39 is an exploded perspective view of a locking mechanism inaccordance with the principles of the present disclosure;

FIG. 40 is a partial cross-sectional view of the locking mechanism ofFIG. 39 installed in a seat-track assembly;

FIG. 41 is a cross-sectional view of a portion of a track of theseat-track assembly of FIG. 40 illustrating locking features;

FIG. 42 is an exploded perspective view of a locking mechanism inaccordance with the principles of the present disclosure;

FIG. 43 is a partial cross-sectional view of the locking mechanism ofFIG. 42 installed in a seat-track assembly;

FIG. 44 is a cross-sectional view of a portion of a track of theseat-track assembly of FIG. 43 in a first position;

FIG. 45 is a cross-sectional view of a portion of the track in a secondposition; and

FIG. 46 is a cross-sectional view of a portion of the track in a thirdposition.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

With particular reference to FIGS. 1 and 2, a seat-track assembly 10 foruse with a seat assembly 12 is provided. The seat-track assembly 10 mayinclude a first track assembly 14 and a second track assembly 16 thatcooperate to selectively permit fore and aft adjustment of the seatassembly 12 relative to an external structure such as, for example, afloorpan of a vehicle (neither shown). The first track assembly 14 andthe second track assembly 16 may be identical in both structure andfunction. Accordingly, only the first track assembly 14 will bedescribed and shown in detail.

The first track assembly 14 may include a lower track 18 fixedlyattached to a floorpan of a vehicle (neither shown), an upper track 20slidably supported by the lower track 18 relative to the floorpan, and alocking mechanism 22 at least partially disposed between the lower track18 and the upper track 20. In operation, the locking mechanism 22 mayselectively fix a position of the upper track 20 relative to the lowertrack 18 when in a locked state and may permit movement of the uppertrack 20 relative to the lower track 18 when in an unlocked state.

The lower track 18 may be attached to the floorpan via a suitableprocess such as, for example, welding and/or staking. The lower track 18may include a bottom wall 24 and a pair of sidewalls 26 that extendgenerally from the bottom wall 24. The bottom wall 24 may include aseries of openings 25 and may be integrally formed with the sidewalls26. As such, the bottom wall 24 may cooperate with the sidewalls 26 toform a channel 28 extending substantially along a length of the lowertrack 18. The sidewalls 26 may also include a channel 30 extending alonga length of each sidewall 26 and may include a series of lockingfeatures 32 separated by a series of projections 34.

The locking features 32 may each include a width substantially equal to10 mm, for example, such that center portions of adjacent lockingfeatures 32 are separated by approximately 20 mm (FIG. 17). As shown inFIG. 17, adjacent locking features 32 are separated from one another bya projection 34, which likewise may include a width substantially equalto 10 mm. As will be described in greater detail below, each lockingfeature 32 may be separated into a first half (A) and a second half (B)to respectively receive and position a portion of the locking mechanism22 therein to selectively prevent movement of the upper track 20relative to the lower track 18.

As described above, the lower track 18 slidably receives the upper track20 to permit selective movement of the upper track 20 relative to thelower track 18. Such movement may be facilitated by a ball-cage assembly(not shown) that may be at least partially received within the channels30 of the sidewalls 26.

The ball-cage assembly may include a housing and a series of ballbearings (neither shown). The ball bearings are constrained by thehousing but are permitted to rotate relative thereto. Such rotation ofthe ball bearings relative to the housing facilitates movement of theupper track 20 relative to the lower track 18 when the locking mechanism22 is in the unlocked state.

With particular reference to FIGS. 4 and 5, the upper track 20 is shownto include a top wall 36 and a pair of sidewalls 38. The top wall 36 maybe integrally formed with the sidewalls 38, whereby each of thesidewalls 38 includes a channel 40 extending substantially along alength of the upper track 20. The top wall 36 may include a series ofapertures 42 that receive a portion of the locking mechanism 22 thereinwhile the sidewalls 38 may include a series of slots 44 that may besubstantially aligned with the apertures 42 and may likewise receive aportion of the locking mechanism 22 therein. Finally, the upper track 20may include a series of fasteners (not shown) that may be used to attacha portion of the seat assembly 12 (FIG. 1) to the upper track 20. Thefasteners may be used to attach a portion of the seat assembly 12 to theupper track 20 to allow the seat assembly 12 to be moved with the uppertrack 20 when the upper track 20 is moved relative to the lower track18.

With particular reference to FIGS. 3-5, the locking mechanism 22 isshown to include a series of locking pawls 46, a series of biasingmembers 48, and a mounting bracket 50. The locking pawls 46 may bereceived within the upper track 20 generally between the top wall 36 andthe sidewalls 38 and may include a main body 52, a pair of oppositelyextending locking arms or locking elements 54, and an actuation arm 56.The locking arms 54 and actuation arm 56 may be integrally formed withthe main body 52 (FIG. 6). Alternatively, the actuation arm 56 may beattached to the main body 52 via a suitable process such as, forexample, staking and/or welding (FIGS. 4 and 5). As used herein and inthe claims, the terms “locking arm” or “locking element” refer to eachindividual laterally extending projection of the locking pawl 46 that isdesigned to be received within and engage a locking feature 32 of thelower track 18 as described herein.

In one configuration, the biasing members 48 may be coil springs thatgenerally surround a portion of the actuation arm 56 and are receivedwithin a pocket 58 (FIG. 4) of the locking pawls 46. The biasing members48 are retained within the pocket 58 once the mounting bracket 50 ispositioned relative to each locking pawl 46 and biasing member 48 toallow the mounting bracket 50 to properly position and retain thelocking pawl 46 and biasing member 48 relative to the upper track 20.

The mounting bracket 50 may include a bottom wall 60 and a pair ofupwardly extending arms 62. A portion of each arm 62 may extend throughapertures 64 of the top wall 36 of the upper track 20 to permit the arms62 to be staked or otherwise attached to the upper track 20. Attachingthe arms 62 of the mounting bracket 50 to the upper track 20 retains thelocking pawls 46 and biasing members 48 in a desired position generallybetween the bottom wall 60 of the mounting bracket 50 and the top wall36 of the upper track 20.

While the locking mechanism 22 is described and shown as including alocking pawl 46 having a main body 52, a pair of locking arms 54, and anactuation arm 56 that is staked to (FIGS. 4 and 5) or integrally formedwith (FIG. 6) the main body 52, the locking mechanism 22 couldalternatively include a locking pawl having any of the configurationsshown in FIGS. 7-13. In view of the substantial similarity in structureand function of the components associated with the locking pawl 46 withrespect to the locking pawls shown in FIGS. 7-13, like referencenumerals are used hereinafter and in the drawings to identify likecomponents while like reference numerals containing letter extensionsare used to identify those components that have been modified.

For example, the locking pawls 46 could be replaced by the locking pawl46 a shown in FIG. 7. The locking pawl 46 a is similar to the lockingpawl 46 in that the locking pawl 46 a includes a main body 52 a having apair of integrally formed locking arms 54 a. However, the locking pawl46 a does not include an actuation arm that is staked or otherwisefixedly attached to the main body 52 a but, rather, includes anintegrally formed actuation arm 56 a. The actuation arm 56 a may beformed from a portion of the main body 52 a, thereby forming a void 66in the main body 52 a where material is taken to form the actuation arm56 a.

With particular reference to FIG. 8, another locking pawl 46 b isprovided and may include a top cap 68 and a locking plate 70. The topcap 68 may receive a portion of the biasing member 48 therein and mayextend through the apertures 42 of the upper track 20 once assembledthereto. The locking plate 70 may generally surround the top cap 68 andmay be positioned by a series of tabs 72 of the top cap 68. The lockingplate 70 may include a pair of locking arms 54 b as well as a centralaperture 74 that receives the top cap 68.

With particular reference to FIG. 9, a locking pawl 46 c is shown toinclude a main body 52 c having a first component 76 formed from a metalmaterial and a second component 78 formed from a plastic material.During assembly, the second component 78 may be molded onto the firstcomponent 76 such that a portion of the first component 76 and a portionof the second component 78 extend through the apertures 42 of the uppertrack 20 to form an actuation arm 56 c. The first component 76 maycooperate with the second component 78 to receive and properly positionthe biasing member 48 relative to the locking pawl 46 c and mountingbracket 50. Once attached to the upper track 20, the first component 76and the second component 78 may extend through the apertures 42 whilelocking arms 54 c of the first component 76 are slidably received withinthe slots 44 of the upper track 20.

With particular reference to FIG. 10, a locking pawl 46 d is provided.The locking pawl 46 d may include a main body 52 d and a locking plate80. The main body 52 d may be formed from plastic and may include anintegrally formed actuation arm 56 d. The locking plate 80 may include apair of locking arms 54 d and may be attached to the main body 52 d formovement therewith. The main body 52 d and the locking plate 80 mayreceive a portion of the biasing member 48 therein to permit the biasingmember 48 to apply a force on the main body 52 d and, thus, the lockingplate 80, when the main body 52 d and the locking plate 80 are disposedbetween the mounting bracket 50 and the upper track 20. Once assembled,the actuation arm 56 d may extend through the apertures 42 of the uppertrack 20 while the locking arms 54 d are slidably received within theslots 44 of the upper track 20.

With particular reference to FIGS. 11 and 12, a pair of locking pawls 46e and 46 f are provided. The locking pawls 46 e, 46 f respectivelyincorporate a top cap 68 e, 68 f and are each fixed for movement with arespective locking plate 70 e, 70 f. The locking plates 70 e, 70 f mayinclude a pair of locking arms 54 e and 54 f, respectively, and may bebiased along with the top caps 68 e, 68 f, by the biasing member 48 onceassembled to the upper track 20 by the mounting bracket 50. The lockingpawls 46 e, 46 f are virtually identical in that a top portion of eachtop cap 68 e, 68 f includes an actuation arm 56 e, 56 f that extendsthrough the apertures 42 of the upper track 20 and a pair of lockingarms 54 e, 54 f that are slidably received within the slots 44 of theupper track 20 when assembled to the upper track 20. The only differencebetween the locking pawl 46 e and the locking pawl 46 f is that the topcap 68 e of the locking pawl 46 e is formed from a plastic material,while the top cap 68 f of the locking pawl 46 f is formed from a metalmaterial such as, for example, steel.

With reference to FIG. 13, a locking pawl 46 g is provided. The lockingpawl 46 g may include a main body 52 g, a pair of locking arms 54 g, andan actuation arm 56 g. As with the locking pawl 46 a (FIG. 7), each ofthe locking arms 54 g and the actuation arm 56 g are integrally formedwith the main body 52 g. However, the locking pawl 46 g additionallyincludes a pair of support arms 82 that serve to further retain thebiasing member 48 within the main body 52 g once the locking pawl 46 gis attached to the upper track 20 via the mounting bracket 50. Onceassembled, the actuation arm 56 g may extend through the apertures 42 ofthe upper track 20 while the locking arms 54 g are slidably receivedwithin the slots 44 of the upper track 20.

While the locking mechanism 22 may include any of the foregoing lockingpawls 46, 46 a, 46 b, 46 c, 46 d, 46 e, 46 f, 46 g, the lockingmechanism 22 will be described and shown hereinafter as incorporatingfour locking pawls 46 each having an actuation arm 56 that is staked orotherwise attached to the main body 52 (FIGS. 4 and 5). The four lockingpawls 46 are positioned relative to the upper track 20 such that aportion of the actuation arm 56 extends through respective apertures 42of the upper track 20 (FIGS. 2-4). Further, the locking pawls 46 arepositioned relative to the upper track 20 such that the locking arms 54extend through and are slidably received within the slots 44 of theupper track 20 (FIGS. 4 and 14).

Once the locking pawls 46 are properly positioned relative to the uppertrack 20 such that the actuation arms 56 extend through the apertures 42and the locking arms 54 extend through the slots 44, the biasing members48 may be respectively inserted over the actuation arms 56 (FIG. 4). Atthis point, the mounting bracket 50 may be positioned relative to eachlocking pawl 46 (FIG. 4) and may be attached to the upper track 20 (FIG.2) to retain the locking pawls 46 and biasing members 48 generallybetween the top wall 36 of the upper track 20 and the bottom wall 60 ofthe mounting bracket 50. At this point, the biasing members 48 exert aforce on the main body 52 of each locking pawl 46, thereby urging thelocking pawls 46 toward the top wall 36 of the upper track 20.

Causing the main body 52 to move toward and engage the top wall 36 ofthe upper track 20 likewise causes the actuation arms 56 of the lockingpawls 46 to extend from the top wall 36 of the upper track 20 throughthe apertures 42. The actuation arms 56 and, thus, the main body 52 andlocking arm 54 of each locking pawl 46 may be moved away from the topwall 36 of the upper track 20 if a force is applied to the actuationarms 56 generally at the portion of the actuation arms 56 that extendsthrough the apertures 42. Such a force must be sufficient to overcomethe force applied to the main body 52 via the biasing member 48 and,once applied, causes the actuation arms 56 to retreat at least partiallyinto the upper track 20 between the top wall 36 and the sidewalls 38.Because the actuation arms 56 are fixed for movement with the main body52 and locking arms 54, movement of the actuation arms 56 into the uppertrack 20 causes the main body 52 to move away from the top wall 36 andcauses the locking arms 54 to traverse the slots 44 and move away fromthe top wall 36 toward the channels 40 of the sidewalls 38 of the uppertrack 20.

With particular reference to FIG. 1, the seat-track assembly 10 is shownincorporated into the seat assembly 12. The seat assembly 12 may befixedly attached to the upper track 20 such that the seat assembly 12 isfixed for movement with the upper track 20 relative to the lower track18. The seat assembly 12 may include an actuation assembly 84 (FIG. 2)that permits selective movement of the actuation arms 56 relative to theupper track 20. The actuation assembly 84 may include one or morebrackets 86 that include a number of apertures 88. The apertures 88 maybe positioned relative to one another such that each aperture 88receives an actuation arm 56. As such, interaction between the apertures88 and the actuation arms 56 of the locking pawls 46 fixes the brackets86 of the actuation assembly 84 for movement with the actuation arms 56of the locking pawls 46.

The brackets 86 may be attached to an arm 90 of the actuation assembly84 that coordinates movement between the brackets 86. Coordinationbetween the respective brackets 86 permits the actuation assembly 84 tomove the locking pawls 46 from a locked state to an unlocked statesubstantially simultaneously to allow selective adjustment of the uppertrack 20 and, thus, the seat assembly 12, in a fore-aft directionrelative to and within the lower track 18, as will be described ingreater detail below. In one configuration, the arm 90 may be pivotablysupported by a pair of mounting flanges 92 that are attached to orintegrally formed with the upper track 20. The mounting flanges 92 mayreceive a pivot 94 to rotatably support the arm 90 relative to the topwall 36 of the upper track 20.

With particular reference to FIGS. 15-17, operation of the seat-trackassembly 10 will be described in detail. When the main bodies 52 of thelocking pawls 46 are biased toward the top wall 36 of the upper track 20via the biasing member 48, the actuation arms 56 extend from the topwall 36 and exert an upward force on the brackets 86 of the actuationassembly 84. In this position, the locking arms 54 of the locking pawls46 are disposed within an upper portion of the slots 44 and are receivedin respective locking features 32 of the lower track 18. Positioning thelocking arms 54 within respective locking features 32 of the lower track18 places the seat-track assembly 10 in the locked state and, thus,restricts translation of the upper track 20 relative to the lower track18.

While the locking arms 54 of the locking pawls 46 are described asengaging the locking features 32, the locking mechanism 22 is designedsuch that only two of the locking pawls 46 engage the locking features32 of the lower track 18 at any given time. As such, four locking arms54 (i.e., two locking arms 54 of two locking pawls 46) are respectivelyreceived within four locking features 32 of the lower track 18. When thelocking arms 54 are received within the locking features 32, the uppertrack 20 is restricted from moving relative to the lower track 18 by thefour locking arms 54.

The locking features 32 may include at least one tapered surface 96 suchthat each locking feature 32 decreases in width in the direction (X)shown in FIG. 17. Providing each locking feature 32 of the lower track18 with a decreasing width in the direction (X) allows the biasingmembers 48 to urge the locking arms 54 into the locking features 32 andinto engagement with the lower track 18, regardless of dimensionaltolerances between the locking pawls 46 or lower track 18. Namely, thelocking arms 54 continue to move into the locking features 32 until thelocking arms 54 are wedged within each locking feature 32 and aresecurely in contact with a projection 34 of the lower track 18. Theforegoing relationship reduces rattling amongst the various componentsand, therefore, reduces chucking during use.

As described, only two of the four locking pawls 46 engage the lockingfeatures 32 of the lower track 18 at any given time. The other twolocking pawls 46 are essentially out-of-phase with the locking features32 and engage the projections 34 disposed between the locking features32 (FIG. 16). The locking arms 54 may include a substantially 5 mm widthsuch that when the locking arms 54 are received within the lockingfeatures 32, a total clearance of 5 mm exists within each lockingfeature 32. Specifically, because each locking feature 32 includes asubstantially 10 mm width, when a 5 mm locking arm 54 is received withinthe 10 mm locking feature 32, a total of a 5 mm clearance is providedbetween the locking arm 54 and the lower track 18.

When the locking arm 54 is initially received within the locking feature32, the locking arm 54 is permitted to move generally within the lockingfeature 32—caused by relative movement between the upper track 20 andthe lower track 18—until the locking arm 54 moves into one of sector (A)or sector (B) and engages an adjacent projection 34. Movement of thelocking arm 54 into one of sector (A) or sector (B) dictates which ofthe other locking arms 54 will engage the locking features 32 of thelower track 18 and which of the other locking arms 54 will beout-of-phase and engage the projections 34. For example, if the lockingarms 54 of a first locking pawl 46 are received within sector (A) of oneof the locking features 32, a second locking pawl 46 may engage alocking feature 32. However, if the locking arms 54 of the first lockingpawl 46 are received within sector (B) of the same locking feature 32,the second locking pawl 46 may be out-of-phase and may engage aprojection 34. In this state, one of the other locking pawls 46 (i.e., athird locking pawl 46 or fourth locking pawl 46) will engage anotherlocking feature 32 to place the locking mechanism 22 in the lockedstate.

The foregoing relationship provides the seat-track assembly 10 with a 5mm increment during adjustment with a maximum of 2.5 mm of travel toallow a second locking pawl 46 to engage the locking features 32.Specifically, if the first locking pawl 46 is received within a lockingfeature 32 at the center of the locking feature 32, the locking pawl 46need only travel 2.5 mm in either direction before contacting anadjacent projection 34 and fully moving into sector (A) or sector (B).In light of the foregoing description, it will be appreciated that thelocking mechanism 22 is a positive engagement latch (PEL) mechanism.That is, at least one of the pawls 46 will be received in the lockingfeatures 32 in the lower track 18 upon release of the actuation assembly84 regardless of the position of the upper track 20 relative to thelower track 18.

Once two of the locking pawls 46 are securely received within tworespective locking features 32 of the lower track 18, the upper track 20and, thus, the seat assembly 12 are restricted from moving relative tothe lower track 18. The seat assembly 12 may only be moved relative tothe lower track 18 when a force is applied to the actuation assembly 84,thereby causing the brackets 86 to apply a force on the actuation arms56 of the locking pawls 46. Application of a force on the actuation arms56 causes the actuation arms 56 to likewise apply a force on the biasingmembers 48 via the main body 52, which causes compression of the biasingmembers 48. Movement of the main body 52 against the biasing members 48likewise causes movement of the locking arms 54 in a direction generallyaway from the top wall 36 of the upper track 20 and within each slot 44.

Sufficient movement of the locking arms 54 within each slot 44 in adirection substantially away from the top wall 36 of the upper track 20causes the locking arms 54 to move into the unlocked state and disengagethe locking features 32, thereby permitting movement of the upper track20 and, thus, the seat assembly 12, relative to the lower track 18. Thelocking pawls 46 are automatically returned to the locked state when theforce applied to the brackets 86 is released due to the biasing members48. Specifically, once the force exerted on the actuation arms 56 by thebrackets 86 is released, the biasing members 48 are once again permittedto bias the main body 52 and, thus, the locking arms 54 of each lockingpawl 46 into a locked state. Namely, the biasing members 48 arepermitted to move the locking arms 54 within each slot 44 generallytoward the top wall 36 of the upper track 20 and allow two of thelocking pawls 46 to engage the locking features 32. Once the lockingarms 54 are received within the locking features 32, the upper track 20and, thus, the seat assembly 12, are once again restricted from movingrelative to the lower track 18.

With particular reference to FIGS. 18-25 another seat-track assembly 110for use with a seat assembly 112 is provided. The seat-track assembly110 may include a first track assembly 114 and a second track assembly116 that cooperate to selectively permit fore and aft adjustment of theseat assembly 112 relative to an external structure such as, forexample, a floorpan of a vehicle (neither shown). The first trackassembly 114 and the second track assembly 116 may be identical in bothstructure and function. Accordingly, only the first track assembly 114will be described and shown in detail.

The first track assembly 114 may include a lower track 118 fixedlyattached to a floorpan of a vehicle (neither shown), an upper track 120slidably supported by the lower track 118 relative to the floorpan, anda locking mechanism 122 at least partially disposed between the lowertrack 118 and the upper track 120. In operation, the locking mechanism122 may selectively fix a position of the upper track 120 relative tothe lower track 118 when in a locked state and may permit movement ofthe upper track 120 relative to the lower track 118 when in an unlockedstate.

The lower track 118 may be attached to the floorpan via a suitableprocess such as, for example, welding and/or staking and may include oneor more projections 119 to facilitate attachment of the lower track 118to the floorpan. The lower track 118 may include a bottom wall 124having a series of openings 125 and a pair of sidewalls 126 that extendgenerally from the bottom wall 124. The bottom wall 124 may beintegrally formed with the sidewalls 126 and may cooperate with thesidewalls 126 to form a channel 128 extending substantially along alength of the lower track 118. The sidewalls 126 may also include achannel 130 extending along a length of each sidewall 126 and mayinclude a series of locking features 132 separated by a series ofprojections 134.

The locking features 132 may each include a width substantially equal to5 mm, for example, such that center portions of adjacent lockingfeatures 132 are separated by approximately 10 mm (FIG. 25). As shown inFIG. 25, adjacent locking features 132 are separated from one another bya projection 134, which likewise may include a width substantially equalto 5 mm. As will be described in greater detail below, each lockingfeature 132 may receive and position a portion of the locking mechanism122 therein to selectively prevent movement of the upper track 120relative to the lower track 118.

As described above, the lower track 118 slidably receives the uppertrack 120 to permit selective movement of the upper track 120 relativeto the lower track 118. Such movement may be facilitated by one or moreball-cage assemblies 121 that may be at least partially received withinthe channels 130 of the sidewalls 126. The ball-cage assemblies 121 mayeach include a pair of housings 123 having one or more ball bearings 125(FIG. 21) and a bracket 127 extending between and connecting thehousings 123. The ball bearings 125 are constrained by the housings 123but are permitted to rotate relative thereto. Such rotation of the ballbearings 125 relative to the housings 123 facilitates movement of theupper track 120 relative to the lower track 118 when the lockingmechanism 122 is in the unlocked state.

With particular reference to FIGS. 19 and 20, the upper track 120 isshown to include a top wall 136 and a pair of sidewalls 138. The topwall 136 may be integrally formed with the sidewalls 138, whereby eachof the sidewalls 138 includes a channel 140 extending substantiallyalong a length of the upper track 120. The top wall 136 may include aseries of apertures 142 that receive a portion of the locking mechanism122 therein. The sidewalls 138 may include a series of slots 144 thatmay be substantially aligned with the apertures 142 and may likewisereceive a portion of the locking mechanism 122 therein. Finally, theupper track 120 may include a series of mounting apertures 133 (FIG. 21)that cooperate with fasteners (none shown) to attach a portion of theseat assembly 112 (FIG. 18) to the upper track 120. The fasteners may beused to attach a portion of the seat assembly 112 to the upper track 120to allow the seat assembly 112 to be moved with the upper track 120 whenthe upper track 120 is moved relative to the lower track 118.

With particular reference to FIGS. 20-24, the locking mechanism 122 isshown to include a series of locking pawls 146, a series of biasingmembers 148, and a mounting bracket 150. The locking pawls 146 may bereceived within the upper track 120 generally between the top wall 136and the sidewalls 138 and may each include a main body 152, at least apair of oppositely extending locking arms 154, and preferably threepairs of oppositely extending locking arms, and an actuation arm 156.The locking arms 154 and the actuation arms 156 may be integrally formedwith the main body 152 (FIG. 21). Alternatively, the actuation arms 156may be separately formed from the main body 152 and may be fixed formovement with the main body 152 by inserting a distal end 155 of theactuation arms 156 into respective apertures 157 formed in the main body152. The distal end 155 of each actuation arm 156 may be press-fit intothe respective apertures 157 and/or may be retained via a suitableprocess such as, for example, welding or staking

In one configuration, the biasing members 148 may be coil springs thatgenerally surround a portion of each actuation arm 156 and are receivedwithin a pocket 158 (FIG. 24) of the mounting bracket 150. The biasingmembers 148 are retained within the pocket 158 to allow the biasingmembers 148 to exert a force on each locking pawl 146—via each actuationarm 156—to bias each locking pawl 146 in the W direction shown in FIG.24.

The mounting bracket 150 may include a bottom wall 160, a top wall 162,and a pair of stop features 164. The bottom wall 160 may be disposed ata bottom of the pocket 158 and may interact with the biasing members 148to retain and position each biasing member 148 within the mountingbracket 150. The top wall 162 may abut the top wall 136 of the uppertrack 120 and may be attached to the top wall 136 via a pair of rivets166. Specifically, the rivets 166 may be respectively received withinthe apertures 142 of the upper track 120 to retain and position themounting bracket 150 relative to the upper track 120.

The stop features 164 may be spaced apart from the bottom wall 160 by apredetermined distance and may cooperate with the bottom wall 160 todefine the pocket 158 in which the biasing members 148 are disposed. Thestop features 164 may interact with the actuation arms 156 to limitmovement of the actuation arms 156 in a direction opposite direction W(FIG. 24) when the biasing members 148 are compressed (FIG. 22).

An actuation mechanism 168 may be supported by the mounting bracket 150to move the locking pawls 146 from a locked state (FIG. 23) to anunlocked state (FIG. 22). The actuation mechanism 168 may include anactuation pin 170 and a rocker arm 172 that cooperate to selectivelyexert a force on the actuation arms 156 to move the locking pawls 146from the locked state to the unlocked state. In light of the foregoingdescription, it will be appreciated that the locking mechanism 122 canbe preassembled as a cartridge or module by fastening the mountingbracket 150 to the upper track 120 with the rivets 166, as describedabove. Providing the locking mechanism 122 as a preassembled cartridgecan simplify manufacturing and assembly of the seat-track assembly 110.

The actuation pin 170 may include an engagement surface 174 and a slot176. The engagement surface 174 may protrude from the top wall 136 ofthe upper track 120 when the actuation pin 170 is inserted into one ofthe apertures 142 formed in the top wall 136 of the upper track 120. Theslot 176 may be blind slot that extends into the actuation pin 170 andincludes an arcuate inner surface 178 (FIG. 24). The rocker arm 172 maybe pivotably attached to the actuation pin 170 via the slot 176.Specifically, the rocker arm 172 may include a pivot 180 that isrotatably attached to the slot 176 at the arcuate inner surface 178. Therocker arm 172 may additionally include a first extension 182 and asecond extension 184 that are in contact with respective actuation arms156 of the locking mechanism 122. As will be described in greater detailbelow, the first extension 182 and the second extension 184 mayselectively transmit a force to the locking pawls 146 via the actuationarms 156 to move the locking arms 154 into the unlocked state (FIG. 22)when a force is applied to the actuation pin 170 at the engagementsurface 174.

With particular reference to FIGS. 22-25, operation of the seat-trackassembly 110 will be described in detail. When the seat-track assembly110 is in the locked state, one of the locking pawls 146 is in thelocked state such that the locking arms 154 of the locking pawl 146 arereceived within respective locking features 132 of the lower track 118(FIG. 23). The locking arms 154 may be in contact with the lower track118 at two points within each locking feature 132 to restrict relativemovement between the lower track 118 and the upper track 120 in twoopposite directions. Namely, interaction between each locking arm 154and the lower track 118 within each locking feature 132 of the lowertrack 118 restricts relative movement between the lower track 118 andthe upper track 120 in the direction (S) and in the direction (T), asshown in FIG. 23.

The locking features 132 of the lower track 118 may include a pair oftapered surfaces 186 that cause each locking feature 132 to have adecreasing width in a direction (Q) moving away from the bottom wall 124(FIG. 25). As such, when the biasing members 148 exert a force on thelocking pawls 146 to urge the locking arms 154 into the locking features132, the locking arms 154 continue movement into the locking features132 until the locking arms 154 are in contact with the lower track 118at two locations within each locking feature 132 at the tapered surfaces186 (FIG. 23).

The locking pawls 146 are biased into the locked state and, as a result,into the locking features 132 of the lower track by the biasing members148. Specifically, the biasing members 148 are disposed within thepocket 158 of the mounting bracket 150 and exert a force on eachactuation arm 156. Exerting a force on the actuation arms 156 causes theactuation arms 156 to likewise apply a force on the rocker arm 172 atthe first extension 182 and the second extension 184. If the lockingarms 154 of the locking pawls 146 are aligned with the locking features132 of the lower track 118, the biasing members 148 cause the actuationarms 156 to apply a force on one of the extensions 182, 184 to rotatethe rocker arm 172 about the pivot 180 relative to the actuation pin170. Continued movement of the actuation arms 156 generally away fromthe bottom wall 124 of the lower track 118 causes the locking arms 154to move into respective locking features 132 of the lower track 118 torestrict relative movement between the lower track 118 and the uppertrack 120.

As shown in FIG. 23, only one of the locking pawls 146 is aligned withthe locking features 132 when the locking mechanism 122 is in the lockedstate. As such, when the locking arms 154 of one of the locking pawls146 are received within the locking features 132 and, therefore, are inthe locked state, the locking arms 154 of the other locking pawl 146 arenot aligned with the locking features 132 of the lower track 118 but,rather, are aligned and are in contact with the projections 134 of thelower track 118. As a result, when the locking mechanism 122 is in thelocked state, only one of the locking pawls 146 is in the locked statesuch that the locking arms 154 are received within the locking features132.

The locking mechanism 122 may be moved from the locked state (FIG. 23)to the unlocked state (FIG. 22) when a force is applied to the actuationpin 170 at the engagement surface 174. The force applied to theactuation pin 170 may be generated by an actuation assembly (not shown)similar to the actuation assembly 84 associated with the seat-trackassembly 10 of FIG. 1. Such an actuation assembly may be supportedrelative to the upper track via a mounting bracket 188 (FIG. 19) toallow the actuation assembly to selectively exert a force on theactuation pin 170.

Regardless of the particular configuration of the actuation assembly,when a force is applied to the actuation pin 170 at the engagementsurface 174 in the direction shown in FIG. 22, the actuation pin 170moves toward the top wall 136 of the upper track 120 and, as a result,causes the slot 176 to likewise move further into the mounting bracket150. Movement of the slot 176 further into the mounting bracket 150relative to the upper track 120 causes the arcuate inner surface 178 ofthe slot 176 to exert a force on the pivot 180 to cause the pivot 180 tomove with the actuation pin 170. Moving the pivot 180 with the actuationpin 170 in the direction shown in FIG. 22 likewise causes the rocker arm172 to move with the actuation pin 170.

Movement of the pivot 180 causes the rocker arm 172 to likewise movefurther into the mounting bracket 150, which causes the first extension182 and the second extension 184 to exert a force on the respectiveactuation arms 156 of the locking mechanism 122. The force is exerted onthe actuation arms 156 via the first extension 182 and the secondextension 184 of the rocker arm 172 and causes the actuation arms 156 tocompress the biasing members 148 within respective pockets 158 of themounting bracket 150. In so doing, the rocker arm 172 causes the lockingarms 154 of the locking pawls 146 to disengage the locking features 132of the lower track 118. Once the locking arms 154 of the locking pawls146 disengage the respective locking features 132 of the lower track118, relative movement between the lower track 118 and the upper track120 is permitted. As such, a force may be applied to the seat assembly112 to adjust a position of the seat assembly 112 relative to the lowertrack 118 by moving the seat assembly 112 along with the upper track 120relative to the lower track 118.

Once a desired position of the seat assembly 112 and, thus, a desiredposition of the upper track 120 relative to the lower track 118 isachieved, the force applied to the actuation pin 170 may be released.When the force applied to the actuation pin 170 is released, the biasingmembers 148 once again exert a force on the actuation arms 156, therebycausing the actuation arms 156 to likewise exert a force on the firstextension 182 and the second extension 184 of the rocker arm 172. If thelocking pawls 146 are positioned relative to the locking features 132and the projections 134 of the lower track 118 such that each lockingarm 154 opposes a projection 134, the biasing members 148 cause thelocking arms 154 to engage the projections 134, thereby preventing thelocking arms 154 from being received within the locking features 132 andreturning the locking mechanism 122 to the locked state.

At this point, a force may be applied to the upper track 120 via theseat assembly 112 to move the upper track 120 relative to the lowertrack 118. Movement of the upper track 120 relative to the lower track118 causes the locking arms 154 of the locking pawls 146 to travel alongthe projections 134 until one of the locking pawls 146 is properlyaligned with the locking features 132 such that the locking arms 154 ofthe one locking pawl 146 may be received within respective lockingfeatures 132 of the lower track 118.

When the upper track 120 is sufficiently moved relative to the lowertrack 118 such that one of the locking pawls 146 is aligned with thelocking features 132, the biasing members 148 rotate the rocker arm 172relative to the actuation pin 170 about the pivot 180, thereby movingone of the actuation arms 156 toward the top wall 136 of the upper track120. In so doing, one of the locking pawls 146 is likewise moved towardthe top wall 136 of the upper track 120, which causes the locking arms154 to engage the locking features 132 of the lower track 118, therebyreturning the locking mechanism 122 to the locked state.

As shown in FIG. 25, if the locking arms 154 of both of the lockingpawls 146 initially engage the projections 134 such that the upper track120 must be moved relative to the lower track 118 to allow one of thelocking pawls 146 to be aligned with the locking features 132, movementof the upper track 120 relative to the lower track 118 is limited toapproximately five millimeters (5 mm). Specifically, because thedistance between the centers of adjacent locking features 132 isapproximately equal to ten millimeters (10 mm), movement of the uppertrack 120 in either the direction (S) or the direction (T; FIG. 23) islimited to approximately five millimeters (5 mm) until one of thelocking pawls 146 engages the locking features 132 of the lower track118. Once one of the locking pawls 146 is received by the lockingfeatures 132 of the lower track 118, the biasing members 148—via theactuation arms 156—cause the locking arms 154 to move into the lockingfeatures 132 and engage the lower track 118 at two locations within eachlocking feature 132 due to the tapered surfaces 186 of each lockingfeature 132. When one of the locking pawls 146 is in the locked statesuch that the locking arms 154 are in contact with the lower track 118at two locations within each locking feature 132, the locking mechanism122 is returned to the locked state and relative movement between theupper track 120 and the lower track 118 is restricted in the direction(S) and the direction (T).

As shown in FIG. 21, each locking pawl 146 may include six (6) lockingarms 154. Namely, each locking pawl 146 may include three locking arms154 on one side of the locking pawl 146 and may likewise include threelocking arms 154 on the other side of the locking pawl 146. As such,when the locking arms 154 are in the locked state and are respectivelyreceived within locking features 132 of the lower track 118, a total ofsix (6) locking arms 154 are engaged with the locking features 132 ofthe lower track 118 while a total of six (6) locking arms 154 of theother locking pawls 146 are in contact with the projections 134 of thelower track 118. While the locking pawls 146 are described and shown aseach including six (6) locking arms 154, the locking pawls 146 mayinclude a different number of locking arms 154. For example, eachlocking pawl 146 may include four (4) locking arms 154 or,alternatively, may include eight (8) locking arms 154.

Regardless of the particular construction of the locking pawls 146, whenthe locking mechanism 122 is in the locked state, each locking arm 154of one of the locking pawls 146 is received within a respective lockingfeature 132 of the lower track 118 while the locking arms 154 of theother locking pawls 146 are in contact with the projections 134 and,therefore, are not received within the locking features 132 of the lowertrack 118. In short, only one of the locking pawls 146 includes lockingarms 154 that are received within locking features 132 of the lowertrack 118 when the locking mechanism 122 is in the locked state torestrict relative movement between the upper track 120 and the lowertrack 118.

Referring now to FIGS. 26-28, another locking mechanism 222 is providedthat could be incorporated into the seat-track assembly 110 in place ofthe locking mechanism 122. The structure and function of the lockingmechanism 222 may be similar or identical to that of the lockingmechanism 122 described above, apart from any exceptions described belowand/or shown in the figures. Therefore, similar features and functionswill not be described again in detail.

Like the locking mechanism 122, the locking mechanism 222 may include aseries of locking pawls 246, a series of biasing members 248, a mountingbracket or housing 250, and an actuation mechanism 268. As describedabove, the locking mechanism 222 can be preassembled as a cartridge ormodule by fastening the mounting bracket 250 to the upper track 120 withthreaded fasteners 266. Providing the locking mechanism 222 as apreassembled cartridge can simplify manufacturing and assembly of theseat-track assembly 110. The mounting bracket 250 may also include oneor more tabs 267 that protrude upward from a top wall 262 of themounting bracket 250. The tabs 267 may extend through apertures 269 inthe upper track 120 and may facilitate alignment of the mounting bracket250 relative to the upper track 120 during installation of the lockingmechanism 222 into the seat-track assembly 110. In some configurations,the tabs 267 may snap into engagement with the apertures 269 to retainthe locking mechanism 22 in place until the fasteners 266 can beinstalled to more securely fix the locking mechanism 222 to the uppertrack 120.

Referring now to FIGS. 29-33, another locking mechanism 322 is providedthat could be incorporated into a seat-track assembly 310. The structureand function of the seat-track assembly 310 and the locking mechanism322 may be similar or identical to that of the seat-track assembly 110and the locking mechanism 122 described above, apart from any exceptionsdescribed below and/or shown in the figures. Therefore, similar featuresand functions will not be described again in detail.

The seat-track assembly 310 may include lower and upper tracks 318, 320,which may be similar or identical to the lower and upper tracks 118, 120described above. Like the locking mechanism 122, the locking mechanism322 may include a series of locking pawls 346, a series of biasingmembers 348, a mounting bracket or housing 350, and an actuator 368.

The mounting bracket 350 may include a body 351 defining a cavity 353, apair of mounting apertures 355 and tabs 367. The cavity 353 may includea plurality of pockets 358 (similar to pockets 158) that are incommunication with each other (via slots 359) and extend axially throughthe body 351. The tabs 367 may extend from a top wall 362 and may extendthrough apertures 369 in the upper track 320. As described above, thelocking mechanism 322 can be preassembled as a cartridge or module byfastening the mounting bracket 350 to the upper track 320 with threadedfasteners 366.

In the configuration shown in FIGS. 29-33, the locking mechanism 322 hasthree locking pawls 346 that are movable independently of each other.Each of the locking pawls 346 may include a main body 352, a pair oflocking arms 354 (locking elements), and an actuation arm 356. Distalends of the actuation arms 356 may be pressed into (or otherwise fixedwithin) respective apertures formed in the main bodies 352. In someconfigurations, the main body 352, locking arm 354 and actuation arm 356could be integrally formed as a unitary body. Each main body 352 mayhave a single locking arm 354 extending from each opposite end of themain body 342.

The biasing members 348 may be coil springs that surround a portion ofthe actuation arms 356 and are received within the pockets 358 of themounting bracket 350. The biasing members 348 are retained within thepockets 358 to allow the biasing members 348 to exert forces on thelocking pawls 346 (via each actuation arm 356) to bias the locking pawls346 upward toward a locked state.

The actuator 368 may include an elongated bar 370 and a peg 371. Theelongated bar 370 may be disposed within the cavity 353 of the mountingbracket 350 and may be movable therein to force the locking pawls 346from the locked state (i.e., the upward position) toward the unlockedstate (i.e., the downward position). The elongated bar 370 may beelongated in a direction parallel to a longitudinal axes of the tracks318, 320 (i.e., the direction in which the upper track 320 is movablerelative to the lower track 318). The peg 371 may extend from theelongated bar 370 in a direction perpendicular to the longitudinal axesof the tracks 318, 320 and may protrude through an aperture 373 in theupper track 320.

As shown in FIGS. 31-33, the lower track 318 includes a plurality oflocking features 332 (similar to locking features 132) that areseparated by protrusions 334. The locking features 332 may be slots thateach have a width W1 that is at least two times larger than a width W2of each locking arm 354. A width W3 of the protrusions 334 betweenadjacent locking features 332 may be about two times larger than thewidth W1, for example. In some configurations, the width W3 may be lessthan twice the width W1. The size of the locking arms 354 and spacingbetween the locking arms 354 as well as the size of the locking features332 and spacing between the locking features 332 is such that when theupper track 320 is fixed in both directions (forward and rearward)relative to the lower track 318, the locking arms 354 of a first one ofthe locking pawls 346 will be contacting a forward end face 381 of oneof the locking features 332, the locking arms 354 of a second one of thelocking pawls 346 will be contacting a rearward end face 383 of anotherone of the locking features 332, and the locking arms 354 of a third oneof the locking pawls 346 will not be received in any of the lockingfeatures 332. The locking mechanism 322 is a positive engagement latch(PEL) mechanism. That is, at least one of the pawls 346 will be receivedin the locking features 332 in the lower track 318 upon release of theactuator 368 regardless of the position of the upper track 320 relativeto the lower track 318. A second one of the locking pawls 346 willengage another locking feature 332 in response to movement of the uppertrack 320 over a distance (in either direction) of no more than half ofthe locking increment (i.e., half of the distance between adjacentlocked positions of the upper track 320).

Referring now to FIGS. 34-38, another locking mechanism 422 is providedthat could be incorporated into a seat-track assembly 410. The structureand function of the seat-track assembly 410 and the locking mechanism422 may be similar or identical to that of the seat-track assembly 310and the locking mechanism 322 described above, apart from any exceptionsdescribed below and/or shown in the figures. Therefore, similar featuresand functions will not be described again in detail.

The seat-track assembly 410 may include lower and upper tracks 418, 420,which may be similar or identical to the lower and upper tracks 318, 320described above. Like the locking mechanism 322, the locking mechanism422 may include a series of locking pawls 446, a series of biasingmembers 448, a mounting bracket or housing 450, and an actuator 468.

The mounting bracket 450 may include a body 451 defining a cavity 453, apair of mounting apertures 455 and tabs 467. The cavity 453 may includea plurality of pockets 458 that are in communication with each other andextend axially through the body 451. The tabs 467 may extend from a topwall 462 and may extend through apertures 469 in the upper track 420. Asdescribed above, the locking mechanism 422 can be preassembled as acartridge or module by fastening the mounting bracket 450 to the uppertrack 420 with threaded fasteners 466.

In the configuration shown in FIGS. 34-38, the locking mechanism 422 hasthree locking pawls 446 that are movable independently of each other.Each of the locking pawls 446 may include a main body 452, a pluralityof locking arms 454 (locking elements), and an actuation arm 456. Distalends of the actuation arms 456 may be pressed into (or otherwise fixedwithin) respective apertures formed in the main bodies 452. In someconfigurations, the main body 452, locking arm 454 and actuation arm 456could be integrally formed as a unitary body. In the configurationshown, the main body 452 has a pair of locking arm 454 extending fromeach opposite end of the main body 442.

The biasing members 448 may be coil springs that surround a portion ofthe actuation arms 456 and are received within the pockets 458 of themounting bracket 450. The biasing members 448 are retained within thepockets 458 to allow the biasing members 448 to exert forces on thelocking pawls 446 (via each actuation arm 456) to bias the locking pawls446 upward toward a locked state.

The actuator 468 may include an elongated bar 470 and a peg 471. Theelongated bar 470 may be disposed within the cavity 453 of the mountingbracket 450 and may be movable therein to force the locking pawls 446from the locked state (i.e., the upward position) toward the unlockedstate (i.e., the downward position). The elongated bar 470 may beelongated in a direction parallel to a longitudinal axes of the tracks418, 420. The peg 471 may extend from the elongated bar 470 in adirection perpendicular to the longitudinal axes of the tracks 418, 420and may protrude through an aperture 473 in the upper track 420.

As shown in FIGS. 36-38, the lower track 418 includes a plurality oflocking features 432 (similar to locking features 332) that areseparated by protrusions 434. The locking features 432 may be slots thateach have a width W1 that is at least two times larger than a width W2of each locking arm 454. A width W3 of the protrusions 434 betweenadjacent locking features 432 may be about two times larger than thewidth W1, for example. In some configurations, the width W3 may be lessthan twice the width W1. The size of the locking arms 454 and spacingbetween the locking arms 454 as well as the size of the locking features432 and spacing between the locking features 432 is such that when theupper track 420 is fixed in both directions (forward and rearward)relative to the lower track 418, the locking arms 454 of a first one ofthe locking pawls 446 will be contacting a forward end face 481 of oneof the locking features 432, the locking arms 454 of a second one of thelocking pawls 446 will be contacting a rearward end face 483 of anotherone of the locking features 432, and the locking arms 454 of a third oneof the locking pawls 446 will not be received in any of the lockingfeatures 432. In some configurations, the forward and rearward end faces481, 483 may be tapered.

The locking arms 454 that are in contact with the forward end faces 481can absorb a crash load associated with a front-impact event of thevehicle in which the seat-track assembly 410 is installed. The lockingarms 454 that are in contact with the rearward end faces 483 can absorba crash load associated with a rear-impact event of the vehicle.

The locking mechanism 422 is a positive engagement latch (PEL)mechanism. That is, at least one of the pawls 446 will be received inthe locking features 432 in the lower track 418 upon release of theactuator 468 regardless of the position of the upper track 420 relativeto the lower track 418. A second one of the locking pawls 446 willengage another locking feature 432 in response to movement of the uppertrack 420 over a distance (in either direction) of no more than half ofthe locking increment (i.e., half of the distance between adjacentlocked positions of the upper track 420).

Referring now to FIGS. 39-41, another locking mechanism 522 is providedthat could be incorporated into a seat-track assembly 510. The structureand function of the seat-track assembly 510 and the locking mechanism522 may be similar or identical to that of the seat-track assembly 310and the locking mechanism 322 described above, apart from any exceptionsdescribed below and/or shown in the figures. Therefore, similar featuresand functions will not be described again in detail.

The seat-track assembly 510 may include lower and upper tracks 518, 520,which may be similar or identical to the lower and upper tracks 118, 120described above. The locking mechanism 522 may include a first lockingpawl 546, a second locking pawl 547, a plurality of biasing members 548,and a mounting bracket or housing 550. The mounting bracket 550 may begenerally similar to the mounting brackets 350, 450.

The first and second locking pawls 546, 547 may each include a main body552, a plurality of locking arms 554 (locking elements), and anactuation arm 556. Distal ends of the actuation arms 556 may be pressedinto (or otherwise fixed within) respective apertures formed in the mainbodies 552. In some configurations, the main body 552, locking arm 554and actuation arm 556 could be integrally formed as a unitary body. Themain body 352 of the first locking pawl 546 may have a plurality oflocking arms 554 extending from each opposite end of the main body 542.The main body 552 of the second locking pawl 547 may have a singlelocking arm 554 extending from each opposite end of the main body 542.

The biasing members 548 may be coil springs that surround a portion ofthe actuation arms 556 and are received within pockets 558 in themounting bracket 550. The biasing members 548 are retained within thepockets 558 to allow the biasing members 548 to exert forces on thelocking pawls 546, 547 (via each actuation arms 556) to bias the lockingpawls 546, 547 upward toward a locked state.

The actuation arm 556 of the first locking pawl 546 may have an actuator568 integrally formed therewith or fixedly attached thereto. Theactuator 568 may include an elongated bar 570 that extends parallel tolongitudinal axes of the tracks 518, 520. A peg 571 may extend upwardfrom the elongated bar 570 in a direction perpendicular to thelongitudinal axes of the tracks 518, 520. As described above, the peg571 may extend through an aperture in the upper track 520. When theactuator 568 is moved downward (relative to the position shown in FIG.40), both locking pawls 546, 547 can be simultaneously forced downwardinto the unlocked state.

As shown in FIG. 41, the locking arms 554 of the first locking pawl 546each have a first width W1 that is smaller than a second width W2 ofeach of the locking arms 554 of the second locking pawl 547. Asdescribed above, the locking arms 554 of the locking pawls 546, 547 canbe received in locking features (e.g., slots) 532 formed in the lowertrack 518. Forward and rearward end faces 581, 583 of the lockingfeatures 532 may include tapered portions that are angled toward eachother so that the width of the locking feature 532 decreases with thedistance from the opening of the locking feature 532 increases.

The narrowest portion of each locking feature 532 may still be widerthan the first width W1 of the locking arms 554 of the first lockingpawl 546. The width of the narrowest portion of each locking feature 532may be equal to or less than the second width W2 of the locking arms 554of the second locking pawl 547. In this manner, the locking arm 554 ofthe second locking pawl 547 will simultaneously contact both of theforward and rearward end faces 581, 583 of the locking feature 532 inwhich it is received. This simultaneous contact with the forward andrearward end faces 581, 583 will eliminate any “slop” or “free-play”between the lower and upper tracks 518, 520 when the locking mechanism522 is in the locked state. When received in corresponding lockingfeatures 532, the locking arms 554 of the first locking pawl 546 areable to absorb a large amount of energy associated with a crash event orsudden, extreme deceleration of the vehicle in which the seat-trackassembly 510 is installed.

Referring now to FIGS. 42-46, another locking mechanism 622 is providedthat could be incorporated into a seat-track assembly 610. The structureand function of the seat-track assembly 610 and the locking mechanism622 may be similar or identical to that of the seat-track assembly 410and the locking mechanism 422 described above, apart from any exceptionsdescribed below and/or shown in the figures. Therefore, similar featuresand functions will not be described again in detail.

The seat-track assembly 610 may include lower and upper tracks 618, 620,which may be similar or identical to the lower and upper tracks 418, 420described above. The locking mechanism 622 may include a first lockingpawl 646, a second locking pawl 647, a third locking pawl 649, a seriesof biasing members 648, a mounting bracket 650, and an actuator 668. Thebiasing members 648, mounting bracket 650 and actuator 668 may besimilar or identical to the biasing members 448, mounting bracket 450and actuator 468 described above. Furthermore, the first and thirdlocking pawls 646, 649 may be similar or identical to the locking pawls446 described above.

Like the locking pawls 446, the first and third locking pawls 646, 649may each have a pair of locking arms 654 on both ends of the main body652 of each locking pawl 646, 649 (i.e., each locking pawl 646, 649 mayhave a total of four locking arms 654). The second locking pawl 647 mayhave only a single locking arm 654 on each end of the main body 652(i.e., a total of two locking arms 654 on the second locking pawl 647).

In the position shown in FIG. 44, the first and third locking pawls 646,649 are in the locked state (i.e., locking elements 654 of the first andthird locking pawls 646, 649 are engaged with (e.g., received within) arespective one of a series of locking features 632 of the lower track618) and the second locking pawl 647 is in the unlocked state. During afront-impact event, the first locking pawl 646 may absorb a large amountof energy and keep the upper track 620 stationary relative to the lowertrack 618. During a rear-impact event, the third locking pawl 649 mayabsorb a large amount of energy and keep the upper track 620 stationaryrelative to the lower track 618.

In the position shown in FIG. 45, the second and third locking pawls647, 649 are in the locked state (i.e., locking elements 654 of thesecond and third locking pawls 647, 649 are engaged with (e.g., receivedwithin) a respective one of the series of locking features 632 of thelower track 618) and the first locking pawl 646 is in the unlockedstate. During a front-impact event, the third locking pawl 649 mayabsorb a large amount of energy and keep the upper track 620 stationaryrelative to the lower track 618. During a rear-impact event, the secondlocking pawl 647 may bend while absorbing crash energy and allow theupper track 620 to move rearward relative to the lower track 618 onlyuntil the first locking pawl 646 is able to move into the locked state.Thereafter, the first locking pawl 646 will absorb any remaining crashenergy and keep the upper track 620 stationary relative to the lowertrack 618.

In the position shown in FIG. 46, the first and second locking pawls646, 647 are in the locked state (i.e., locking elements 654 of thefirst and second locking pawls 646, 647 are engaged with (e.g., receivedwithin) a respective one of the series of locking features 632 of thelower track 618) and the third locking pawl 649 is in the unlockedstate. During a rear-impact event, the first locking pawl 646 may absorba large amount of energy and keep the upper track 620 stationaryrelative to the lower track 618. During a front-impact event, the secondlocking pawl 647 may bend while absorbing crash energy and allow theupper track 620 to move forward relative to the lower track 618 onlyuntil the third locking pawl 649 is able to move into the locked state.Thereafter, the third locking pawl 649 will absorb any remaining crashenergy and keep the upper track 620 stationary relative to the lowertrack 618.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.embodiments will now be described more fully with reference to theaccompanying drawings.

What is claimed is:
 1. A seat-track assembly comprising: a first trackmember having a plurality of locking features; a second track memberslidably supported by said first track member for relative movementalong an axis; and a locking mechanism disposed at least partiallybetween said first track member and said second track member andincluding four locking pawls, wherein each of said four locking pawls ismovable between a locked state and an unlocked state; wherein, when anyindividual locking pawl of said four locking pawls is in said lockedstate, said individual locking pawl of said four locking pawls isengaged with two of said plurality of locking features to restrictrelative movement between said first track member and said second trackmember; wherein, when all of said four locking pawls are in saidunlocked state, said four locking pawls are disengaged from saidplurality of locking features, such that relative movement between saidfirst track member and said second track member is permitted; whereineach of said four locking pawls has only two oppositely extendinglocking projections oriented transversely and received within respectiveones of said plurality of locking features when in said locked state,said only two oppositely extending locking projections of each of saidfour locking pawls include a first locking projection and a secondlocking projection; wherein each of said plurality of locking featureshas a first width and each of said only two oppositely extending lockingprojections of each of said four locking pawls has a second width thatis no more than half of the first width, the first and second widths aremeasured along said axis; wherein said locking mechanism includesindividual biasing members for separately biasing each of said fourlocking pawls toward said locked state; wherein each of said fourlocking pawls is movable independently from said unlocked state to saidlocked state; wherein all of said first locking projections of said fourlocking pawls are equally spaced apart along said axis by a firstdistance; wherein all of said second locking projections of said fourlocking pawls are equally spaced apart along said axis by said firstdistance; wherein said plurality of locking features have a first seriesof locking features associated with all of said first lockingprojections of said four locking pawls and equally spaced apart alongsaid axis by said first distance; wherein said plurality of lockingfeatures have a second series of locking features associated with all ofsaid second locking projections of said four locking pawls and equallyspaced apart along said axis by said first distance; wherein said firstwidth is substantially equal to said first distance; and wherein saidsecond width is substantially equal to one-half of said first width. 2.The seat-track assembly of claim 1, further comprising an actuatoroperable to selectively apply a force on said four locking pawlsopposing said biasing members to maintain said four locking pawls insaid unlocked state.
 3. The seat-track assembly of claim 2, wherein saidonly two oppositely extending locking projections of each of at leasttwo of said four locking pawls are configured to be received within saidrespective ones of said plurality of locking features following releaseof said force.
 4. The seat-track assembly of claim 3, wherein each ofsaid plurality of locking features in said first track member is definedby a forward face and a rearward face relative to said axis, and furtherwherein said only two oppositely extending locking projections of afirst locking pawl of said at least two of said four locking pawlsengage the forward faces of the respective ones of said plurality oflocking features and said only two oppositely extending lockingprojections of a second locking pawl of said at least two of said fourlocking pawls engage the rearward faces of the respective ones of saidplurality of locking features when said at least two of said fourlocking pawls are in said locked state.
 5. The seat-track assembly ofclaim 4, wherein relative movement in one axial direction between saidfirst track member and said second track member is limited to a seconddistance following release of said force before said only two oppositelyextending locking projections of said second locking pawl of said atleast two of said four locking pawls are received within the respectiveones of said plurality of locking features, to thereby prevent furtherrelative movement between said first track member and said second trackmember.
 6. The seat-track assembly of claim 5, wherein said second widthis substantially equal to said second distance.
 7. The seat-trackassembly of claim 6, wherein said first width is substantially equal to10 mm and said second width is substantially equal to 5 mm.
 8. Theseat-track assembly of claim 1, wherein said locking mechanism furtherincludes a mounting bracket, wherein said four locking pawls and saidbiasing members are mounted to said mounting bracket so as to comprise asubassembly, and further wherein said mounting bracket containing saidsubassembly is fixedly connected to said second track member.
 9. Theseat-track assembly of claim 8, wherein said four locking pawls aremovable in a direction perpendicular to said axis between said lockedstate and said unlocked state.
 10. The seat-track assembly of claim 9,wherein said first track member comprises opposite sidewalls defining alongitudinal channel parallel to said axis and each series of said firstand second series of locking features are arranged in a correspondingone of said opposite sidewalls, and further wherein said only twooppositely extending locking projections of each of said four lockingpawls are received within respective ones of said first and secondseries of locking features in said opposite sidewalls when in saidlocked state.